This is also useful if you have an element on your page that changes height after the initial page load. In my expereience this causes live preview to gradually scroll down the page until you're just left looking at your site's footer.

It's worth having a look through the documentation forcraft.app.request to see what other info you have access to in both your templates and plugin code. You never know when you might need to check whether a request was sent specifically from a Flash application ¯\_(ツ)_/¯